The invention applies more particularly to a radiofrequency receiver device including:                a local oscillator oscillating at an adjustable local frequency,        a mixer receiving radiofrequency signals and the output of the local oscillator for the supply of intermediate-frequency signals,        a filtering system, low-pass or band-pass, configured and positioned to filter the intermediate-frequency or radiofrequency signals according to a bandpass with an adjustable frequency bandwidth, and        a data detector in the intermediate-frequency signals.        
Such an architecture is suitable for heterodyne receivers which use a local oscillator for transposing the radiofrequency signals about a frequency, referred to as intermediate frequency, which is very low as compared to the initial carrier frequency thereof, before detecting data contained therein by returning same if required, when the intermediate frequency is different from zero, to the baseband. In a congested spectral environment, these receivers require very precise local frequency generation and a high frequency selectivity in order to attain a satisfactory sensitivity.